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The U.S. Energy Department's National Renewable Energy Laboratory (NREL, Boulder, Colo., USA) reported on Dec. 26 that it has installed a new 5­-MW Dynamometer Test Facility at its National Wind Technology Center (NWTC). The new facility expands the capability of NWTC engineers and their industry partners to verify the performance and reliability of wind turbine drivetrain prototypes and commercial machines.

The facility is capable of testing drivetrains up to 5 MW—large enough to test virtually any land-­based turbine—and employs dynamically variable loading capabilities that will allow researchers to better simulate conditions a turbine might experience in the field.

"These new capabilities make this a very special facility, one of the largest and finest of its kind in the world," NWTC Director Fort Felker said. "It gives NREL an enhanced ability to do comprehensive testing of modern multi­-megawatt wind turbine systems in a laboratory environment to verify their performance and reliability before they are widely deployed."

A dynamometer system replaces the rotor and blades of a wind turbine and allows researchers to control the turbine drivetrain's mechanical and electrical systems while simulating normal and extreme operating conditions. Historically, this testing has been done under torque (rotating) loads only. The new facility at the NWTC, funded with the support of the Energy Department and the American Recovery and Reinvestment Act (ARRA), incorporates a non­-torque loading system into the testing regimen, a hydraulic device that allows for simulation of both the rotational and bending loads that a wind turbine rotor places on a drivetrain.

"The non­torque loading system is what really sets this facility apart from other comparable test sites," NWTC Dynamometer Project Manager Mark McDade says. "This allows us to test the drivetrain system with the types of loads that it will see in a real­world application. It's a very important feature for a test apparatus because the adverse impacts these types of loads can have on a system are significant."

Dynamometer testing is used by industry to confirm proper operation and reduce the risk of deploying wind turbine prototypes before they are put into service. By reproducing operating conditions in a laboratory environment, engineers can verify the performance of a turbine's systems, including generators, gearboxes, power converters, bearings, brakes, and control systems. Conducting these tests before deployment is important because unanticipated failures can be detected and corrected early in the development process, leading to a lower cost of ownership for wind farm operators—and ultimately lower­cost wind energy for the consumer.

The first tests being done at NREL's new dynamometer facility are on a 2.75-­MW wind turbine the Energy Department acquired in partnership with General Electric (GE). The GE system is being used for the calibration and commissioning of the testing equipment in the facility, which will also provide the industry partner with useful data on this particular turbine model.